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THE AMERICAN NATURALIST 



[Vol. LI 



2. Evidence of hereditary predetermination or po- 



tentiality of the genesis of similar new char- 

 acters in phyla derived from similar ancestors. 



3. Continuous evolution of rectigradations in one 



direction, Mutationsrichtung. 



4. Mutations of Waagen, subspecific gradations of 



character. 



5. Complete separahility of rectigradations in 



heredity, as shown in the teeth of the hybrids 

 of the horse and ass, all rectigradations being 

 either present or absent but not blended. 



3. Summary 



It appears from the foregoing classes of evidence that 

 biocharacters are separable in origin, development, evo- 

 lution, and heredity. First, biocharacters are separable 

 through their many different modes of origin from the 

 germ, either saltatory, gradational, or continuous. Sec- 

 ond, biocharacters have different rates of motion, or 

 velocity, in individual development (ontogeny), exhibit- 

 ing acceleration or retardation. Third, biocharacters 

 have different rates of evolution in different phyla 

 (phylogeny), again exhibiting acceleration or retardation 

 (phyla). Fourth, all the biocharacters of an organism 

 cooperate through various modes of grouping in func- 

 tional correlation, in compensation, in sex linkage. Fifth, 

 in the hard parts of the body while the biocharacters of 

 form and proportion may originate through continuity, 

 through saltation, or through minute gradations, all the 

 known evolution of proportion biocharacters is contin- 

 uous. Sixth, in the hard parts the biocharacters of recti- 

 gradations have only been observed to originate and de- 

 velop through continuity. 



